259 lines
7.0 KiB
Perl
259 lines
7.0 KiB
Perl
#!/usr/bin/perl
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## -----------------------------------------------------------------------
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##
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## Copyright 2002-2008 H. Peter Anvin - All Rights Reserved
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## Copyright 2009 Intel Corporation; author: H. Peter Anvin
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##
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## This program is free software; you can redistribute it and/or modify
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## it under the terms of the GNU General Public License as published by
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## the Free Software Foundation, Inc., 53 Temple Place Ste 330,
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## Boston MA 02111-1307, USA; either version 2 of the License, or
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## (at your option) any later version; incorporated herein by reference.
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##
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## -----------------------------------------------------------------------
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#
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# Post-process an ISO 9660 image generated with mkisofs/genisoimage
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# to allow "hybrid booting" as a CD-ROM or as a hard disk.
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#
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use bytes;
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use Fcntl;
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# User-specifyable options
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%opt = (
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# Fake geometry (zipdrive-style...)
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'h' => 64,
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's' => 32,
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# Partition number
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'entry' => 1,
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# Partition offset
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'offset' => 0,
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# Partition type
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'type' => 0x17, # "Windows hidden IFS"
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# MBR ID
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'id' => undef,
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);
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%valid_range = (
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'h' => [1, 256],
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's' => [1, 63],
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'entry' => [1, 4],
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'offset' => [0, 64],
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'type' => [0, 255],
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'id' => [0, 0xffffffff],
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'hd0' => [0, 2],
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'partok' => [0, 1],
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);
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# Boolean options just set other options
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%bool_opt = (
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'nohd0' => ['hd0', 0],
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'forcehd0' => ['hd0', 1],
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'ctrlhd0' => ['hd0', 2],
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'nopartok' => ['partok', 0],
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'partok' => ['partok', 1],
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);
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sub usage() {
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print STDERR "Usage: $0 [options] filename.iso\n",
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"Options:\n",
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" -h Number of default geometry heads\n",
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" -s Number of default geometry sectors\n",
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" -entry Specify partition entry number (1-4)\n",
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" -offset Specify partition offset (default 0)\n",
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" -type Specify partition type (default 0x17)\n",
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" -id Specify MBR ID (default random)\n",
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" -forcehd0 Always assume we are loaded as disk ID 0\n",
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" -ctrlhd0 Assume disk ID 0 if the Ctrl key is pressed\n",
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" -partok Allow booting from within a partition\n";
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exit 1;
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}
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# Parse a C-style integer (decimal/octal/hex)
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sub doh($) {
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my($n) = @_;
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return ($n =~ /^0/) ? oct $n : $n+0;
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}
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sub get_random() {
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# Get a 32-bit random number
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my $rfd, $rnd;
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my $rid;
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if (open($rfd, "< /dev/urandom\0") && read($rfd, $rnd, 4) == 4) {
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$rid = unpack("V", $rnd);
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}
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close($rfd) if (defined($rfd));
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return $rid if (defined($rid));
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# This sucks but is better than nothing...
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return ($$+time()) & 0xffffffff;
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}
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sub get_hex_data() {
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my $mbr = '';
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my $line, $byte;
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while ( $line = <DATA> ) {
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chomp $line;
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last if ($line eq '*');
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foreach $byte ( split(/\s+/, $line) ) {
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$mbr .= chr(hex($byte));
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}
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}
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return $mbr;
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}
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while ($ARGV[0] =~ /^\-(.*)$/) {
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$o = $1;
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shift @ARGV;
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if (defined($bool_opt{$o})) {
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($o, $v) = @{$bool_opt{$o}};
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$opt{$o} = $v;
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} elsif (exists($opt{$o})) {
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$opt{$o} = doh(shift @ARGV);
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if (defined($valid_range{$o})) {
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($l, $h) = @{$valid_range{$o}};
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if ($opt{$o} < $l || $opt{$o} > $h) {
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die "$0: valid values for the -$o parameter are $l to $h\n";
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}
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}
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} else {
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usage();
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}
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}
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($file) = @ARGV;
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if (!defined($file)) {
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usage();
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}
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open(FILE, "+< $file\0") or die "$0: cannot open $file: $!\n";
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binmode FILE;
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#
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# First, actually figure out where mkisofs hid isolinux.bin
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#
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seek(FILE, 17*2048, SEEK_SET) or die "$0: $file: $!\n";
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read(FILE, $boot_record, 2048) == 2048 or die "$0: $file: read error\n";
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($br_sign, $br_cat_offset) = unpack("a71V", $boot_record);
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if ($br_sign ne ("\0CD001\1EL TORITO SPECIFICATION" . ("\0" x 41))) {
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die "$0: $file: no boot record found\n";
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}
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seek(FILE, $br_cat_offset*2048, SEEK_SET) or die "$0: $file: $!\n";
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read(FILE, $boot_cat, 2048) == 2048 or die "$0: $file: read error\n";
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# We must have a Validation Entry followed by a Default Entry...
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# no fanciness allowed for the Hybrid mode [XXX: might relax this later]
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@ve = unpack("v16", $boot_cat);
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$cs = 0;
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for ($i = 0; $i < 16; $i++) {
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$cs += $ve[$i];
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}
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if ($ve[0] != 0x0001 || $ve[15] != 0xaa55 || $cs & 0xffff) {
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die "$0: $file: invalid boot catalog\n";
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}
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($de_boot, $de_media, $de_seg, $de_sys, $de_mbz1, $de_count,
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$de_lba, $de_mbz2) = unpack("CCvCCvVv", substr($boot_cat, 32, 32));
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if ($de_boot != 0x88 || $de_media != 0 ||
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($de_segment != 0 && $de_segment != 0x7c0) || $de_count != 4) {
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die "$0: $file: unexpected boot catalog parameters\n";
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}
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# Now $de_lba should contain the CD sector number for isolinux.bin
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seek(FILE, $de_lba*2048+0x40, SEEK_SET) or die "$0: $file: $!\n";
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read(FILE, $ibsig, 4);
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if ($ibsig ne "\xfb\xc0\x78\x70") {
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die "$0: $file: bootloader does not have a isolinux.bin hybrid signature.".
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"Note that isolinux-debug.bin does not support hybrid booting.\n";
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}
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# Get the total size of the image
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(@imgstat = stat(FILE)) or die "$0: $file: $!\n";
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$imgsize = $imgstat[7];
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if (!$imgsize) {
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die "$0: $file: cannot determine length of file\n";
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}
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# Target image size: round up to a multiple of $h*$s*512
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$h = $opt{'h'};
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$s = $opt{'s'};
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$cylsize = $h*$s*512;
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$frac = $imgsize % $cylsize;
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$padding = ($frac > 0) ? $cylsize - $frac : 0;
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$imgsize += $padding;
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$c = int($imgsize/$cylsize);
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if ($c > 1024) {
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print STDERR "Warning: more than 1024 cylinders ($c).\n";
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print STDERR "Not all BIOSes will be able to boot this device.\n";
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$cc = 1024;
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} else {
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$cc = $c;
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}
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# Preserve id when run again
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if (defined($opt{'id'})) {
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$id = pack("V", doh($opt{'id'}));
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} else {
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seek(FILE, 440, SEEK_SET) or die "$0: $file: $!\n";
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read(FILE, $id, 4);
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if ($id eq "\x00\x00\x00\x00") {
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$id = pack("V", get_random());
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}
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}
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# Print the MBR and partition table
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seek(FILE, 0, SEEK_SET) or die "$0: $file: $!\n";
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for ($i = 0; $i <= $opt{'hd0'}+3*$opt{'partok'}; $i++) {
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$mbr = get_hex_data();
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}
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if ( length($mbr) > 432 ) {
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die "$0: Bad MBR code\n";
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}
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$mbr .= "\0" x (432 - length($mbr));
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$mbr .= pack("VV", $de_lba*4, 0); # Offset 432: LBA of isolinux.bin
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$mbr .= $id; # Offset 440: MBR ID
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$mbr .= "\0\0"; # Offset 446: actual partition table
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# Print partition table
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$offset = $opt{'offset'};
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$psize = $c*$h*$s - $offset;
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$bhead = int($offset/$s) % $h;
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$bsect = ($offset % $s) + 1;
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$bcyl = int($offset/($h*$s));
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$bsect += ($bcyl & 0x300) >> 2;
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$bcyl &= 0xff;
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$ehead = $h-1;
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$esect = $s + ((($cc-1) & 0x300) >> 2);
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$ecyl = ($cc-1) & 0xff;
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$fstype = $opt{'type'}; # Partition type
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$pentry = $opt{'entry'}; # Partition slot
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for ( $i = 1 ; $i <= 4 ; $i++ ) {
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if ( $i == $pentry ) {
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$mbr .= pack("CCCCCCCCVV", 0x80, $bhead, $bsect, $bcyl, $fstype,
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$ehead, $esect, $ecyl, $offset, $psize);
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} else {
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$mbr .= "\0" x 16;
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}
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}
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$mbr .= "\x55\xaa";
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print FILE $mbr;
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# Pad the image to a fake cylinder boundary
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seek(FILE, $imgstat[7], SEEK_SET) or die "$0: $file: $!\n";
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if ($padding) {
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print FILE "\0" x $padding;
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}
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# Done...
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close(FILE);
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exit 0;
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__END__
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